Here's the Lowdown on Apple Inc's Sapphire Glass

The tough material is much stronger than the Gorilla Glass that the company currently uses, but much more expensive too.

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On Tuesday, shares of the diversified technology company GT Advanced Technologies (NASDAQ:GTAT) increased by nearly 15%. The company is responsible for producing the extremely durable sapphire glass that Apple (NASDAQ:AAPL) currently uses for the fingerprint scanners on its iPhone 5S. Yesterday's spike was a direct result of mounting rumors that Apple will be implementing the glass in either the upcoming iPhone 6, or the still-mythical iWatch, or both.

Since Apple announced late last year that it has plans to open a sapphire glass factory in Arizona, contrasting reports have been released on the efficacy and cost of sapphire glass versus Gorilla Glass, which Apple uses for the current generation of iPhones. Gorilla Glass is standard glass whose strength has been augmented via a chemical process, while sapphire glass is, as the name suggests, derived from sapphire crystals.

In an attempt to clarify the pros and cons of sapphire glass, the Apple news website Cult of Mac interviewed the aerospace company Aero-Gear, which manufacturers its own sapphire screen protector for iPhones. Its story, published this morning, sheds further light on the advantages and disadvantages of sapphire glass.

Thickness and Heaviness

Sapphire glass is approximately 67% heavier than Gorilla Glass, which of course could prove a problem for Apple since it is always trying to lighten and slim down its products. Corning (NYSE:GLW), the manufacturer of Gorilla Glass, claimed in a blog post that Apple would find it difficult to make an iPhone as thin as the iPhone 5S should it choose to use sapphire for the screen of the iPhone 6. Aero-Gear disputed that claim, noting that its Gorilla Glass and sapphire screens are not very different in thickness: The former is .55mm thick while the latter is .6mm.

Strength

Gorilla Glass really takes the cake in the "strength" category, as there is only one material that is stronger than sapphire: diamond. Sapphire is nearly impossible to scratch, and its ability to withstand cracks or breaks is around four times greater than that of Gorilla Glass.

To prove the incredible strength of sapphire, Aero-Gear posted a video on YouTube last August in which someone dragged a concrete cinder block over an iPhone 5 featuring the sapphire display. The screen was completely undamaged. See the video below:

Price

Now, here's where Gorilla Glass has a definite advantage: It is still much cheaper to produce than sapphire. Gorilla Glass is produced by adding one additional chemical process to the usual method of creating standard glass. On the other hand, the sapphire crystals used to produce sapphire glass are made from minerals grown in a furnace. Furthermore, when the resultant material is removed from the furnace, it is not in large sheets the way glass is produced, but in big blocks. Those blocks must then be cut with either a diamond saw or a laser (sapphire for Apple is produced by the latter method) in order to slice the raw material into the proper size.

According to Aero-Gear, even with the massive quantities that Apple would produce, sapphire glass would cost as much as three or four times more to produce than Gorilla Glass.

If the iPhone 6 were to have a screen made of sapphire glass, the cost of production would increase substantially. For this reason, several rumors contend that Apple will not use the material for the iPhone 6 but rather for the anticipated, but as of yet unannounced iWatch, which is rumored to have a two-inch display.

Then again, one of the major complaints about iPhones is their fragility; consumers say the screen simply breaks and scratches too easily. The implementation of sapphire glass could make the iPhone almost entirely scratch-proof. However, the investment to make the iPhone 6 nearly invincible may be too great -- at least for now. As Sebastian Anthony of ExtremeTech wrote last week, "It would be a huge deal if Apple led with a sapphire glass iPhone, but I wouldn't be surprised if we have to wait another year or two until it's economically viable."